Potential impact of the 2023 Lahaina wildfire on the marine environment: Modeling the transport of ash-laden benzo[a]pyrene and pentachlorophenol.

The Lahaina urban/wildland fire event is considered the deadliest wildfire in the past century of U.S. history. This fire resulted in over 2200 building structures destroyed or damaged, approximately 4000 automobiles were incinerated and between 450 and 878 ha of grassland burned in areas adjoining the town of Lahaina, Maui County, State of Hawaii, U.S.A. One of the most abundant contaminants of both wildland and urban fires is the incomplete combustion product, benzo[a]pyrene. Pentachlorophenol from burned and unburned utility poles/residential burn sites enter into navigable waters, thus posing a serious risk to the water quality of coastal waters. The Risk Quotient Plumes for benzo[a]pyrene and pentachlorophenol, mobilized from Lahaina into coastal waters were calculated based on a hydrodynamic analysis and an integrated ecological risk assessment. This plume was simulated using rainfall events in November 2022 as a proxy for the first major rainfall event expected in Lahaina in 2024. The models indicated that the estimated levels of benzo[a]pyrene and pentachlorophenol posed a risk to near shore habitants within 2 km of Lahaina. The levels of pentachlorophenol were more widespread than benzo[a]pyrene and were predicted to pose a hazard to marine life as far away as Molokini Shoal Marine Life Conservation District and 'Ahihi-Kina'u Natural Area Reserve. Fisheries species captured near these areas should be tested for consumption safety.

Oxybenzone contamination from sunscreen pollution and its ecological threat to Hanauma Bay, Oahu, Hawaii, U.S.A.

Hanauma Bay is a 101-acre bay created by the partial collapse of a volcanic cone and once supported a vibrant coral reef system. It is the most popular swimming area in the Hawaiian Islands and has been reported to have averaged between 2.8 and 3.5 million visitors a year between the 1980s and the 2010s, with visitors averaging between 3000-4000 a day and peaking around 10,000-13,000 per day. Concentrations of oxybenzone and other common UV filters were measured in subsurface water samples and in sands from the beach-shower areas in Hanauma Bay. Results demonstrate that beach showers also can be a source of sunscreen environmental contamination. Hydrodynamic modeling indicates that oxybenzone contamination within Hanauma Bay's waters could be retained between 14 and 50 h from a single release event period. Focusing on only oxybenzone, two different Hazard and Risk Assessment analyses were conducted to determine the danger of oxybenzone to Hanauma Bay's coral reef system. Results indicate that oxybenzone contamination poses a significant threat to the wildlife of Hanauma Bay. To recover Hanauma Bay's natural resources to a healthy condition and to satisfactorily conserve its coral reef and sea grass habitats, effective tourism management policies need to be implemented that mitigate the threat of sunscreen pollution.

Cage aquaculture in the Persian Gulf: A cautionary tale for Iran and the world.

Around the world, coral reefs are in decline. Recent interest has focussed on the impacts of global warming/climate change, but the decline started long before the influence of climate change became apparent, driven by anthropogenic factors such as sedimentation, nutrient increase, and overfishing. These continue with no real signs of abatement, as does concomitant reef damage. The Persian Gulf supports widespread coral growth, especially on the Iranian side. Responding to issues of food security, the Iranian government has proposed large-scale aquaculture (open-net fish pens) along their coastline, with an eventual production of 200,000 t/year. Nutrient discharge will be a major issue. We developed a hydrodynamic circulation model for the Persian Gulf which allows us to follow the path of dissolved material. We estimated the amount of nitrogen that would be produced by the projected farms and modelled nitrogen distribution over time, using production rates of 44kgN released/t of fish. In a model run simulating one year at full operation of the proposed number of fish farms, we estimate that most of the reefs on the Iranian side will be bathed in waters with nutrient levels higher than will allow for reef survival. We used a trigger value of 20 µg/l total N. Mangroves will also be affected. There is significant trans-border movement of nutrients, to the waters of neighbouring countries. In fact, withing a few years the entire Gulf will be affected. These planned aquaculture projects have the potential to damage the mangroves and kill every reef in the Persian Gulf in a very short period of time. There is a high probability of affecting fisheries resources in neighbouring countries-a situation to be avoided in politically volatile regions. There seem only two solutions: 1. either run the fish farms so that nutrient discharge is kept to acceptable levels, using an ironclad monitoring system, or 2. bring the operations on land by establishing recirculating aquaculture systems.